<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-scroll-snap-1" />
<link rel="stylesheet" href="resources/simple-snap.css">
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="../../resources/gesture-util.js"></script>

<div id='scroller'>
  <div id="space"></div>
  <div class="snap left top" id="top-left"></div>
  <div class="snap right top" id="top-right"></div>
  <div class="snap left bottom" id="bottom-left"></div>
</div>

<script>
var scroller = document.getElementById("scroller");
var topLeft = document.getElementById("top-left");
var topRight = document.getElementById("top-right");

function scrollLeft() {
  return scroller.scrollLeft;
}

function scrollTop() {
  return scroller.scrollTop;
}

function keyPress(key) {
  return new Promise((resolve, reject) => {
    if (window.eventSender) {
      eventSender.keyDown(key);
      resolve();
    }
    else {
      reject('This test requires window.eventSender');
    }
  })
}

promise_test (async () => {
  // Make the snap area covers the snapport.
  topLeft.style.width = "800px";
  // Make the distance between the previous and the next snap position larger
  // than snapport.
  topRight.style.left = "500px";
  await mouseClickOn(10, 10);
  scroller.scrollTo(0, 0);
  const scrollEventPromise = waitForScrollEvent(scroller);
  await keyPress("ArrowRight");
  await scrollEventPromise;
  // Use time based wait since the scroll does not end at a fixed value.
  await waitForAnimationEndTimeBased(scrollLeft);
  assert_between_exclusive(scroller.scrollLeft, 0, 500);
  topLeft.style.width = "";
  topRight.style.left = "400px";
}, "If the original intended offset is valid as making a snap area cover the"
+ "snapport, and there's no other snap offset in between, use the original"
+ "intended offset");

promise_test (async () => {
  // Make the snap area covers the snapport.
  topLeft.style.width = "800px";
  // Make the next snap offset closer than the original intended offset.
  topRight.style.left = "20px";
  await mouseClickOn(10, 10);
  scroller.scrollTo(0, 0);
  await keyPress("ArrowRight");
  await waitForScrollEnd(scroller, scrollLeft, 20);
  topLeft.style.width = "";
  topRight.style.left = "400px";
}, "If the original intended offset is valid as making a snap area cover the "
+ "snapport, but there's a defined snap offset in between, use the defined snap"
+ " offset.");

promise_test (async () => {
  await mouseClickOn(10, 10);
  scroller.scrollTo(400, 0);
  const scrollEventPromise = waitForScrollEvent(scroller);
  await keyPress("ArrowRight");
  // Use time based wait since returning to the start position.
  await waitForAnimationEndTimeBased(scrollLeft);
  assert_equals(scroller.scrollLeft, 400);
}, "If there is no valid snap offset on the arrow key's direction other than "
+ "the current offset, and the scroll-snap-type is mandatory, stay at the "
+ "current offset.");

promise_test (async () => {
  scroller.style.scrollSnapType = "both proximity";
  await mouseClickOn(10, 10);
  scroller.scrollTo(400, 0);
  const scrollEventPromise = waitForScrollEvent(scroller);
  await keyPress("ArrowRight");
  await scrollEventPromise;
  // Use time based wait since the scroll does not end at a fixed value.
  await waitForAnimationEndTimeBased(scrollLeft);
  assert_greater_than(scroller.scrollLeft, 400);
  scroller.style.scrollSnapType = "both mandatory";
}, "If there is no valid snap offset on the arrow key's direction other than "
+ "the current offset, and the scroll-snap-type is proximity, go to the "
+ "original intended offset");
</script>

